Field of the Invention
The present invention relates to: an image processing apparatus such as a multifunctional digital image forming apparatus (i.e., a multi-function peripheral abbreviated as MFP) having multiple functions, e.g., copier function, printer function, facsimile function, and scanner function; an electronic file generating method for the image processing apparatus; and a recording medium.
Description of the Related Art
The following description sets forth the inventor's knowledge of related art and problems therein and should not be construed as an admission of knowledge in the prior art.
Image data including texts, for example, image data obtained from a text document by a scanner normally becomes larger in size when it is converted into an electronic file format such as joint photographic experts group (JPEG) format or portable document format (PDF).
With respect to this problem, Japanese Unexamined Patent Publications No. 2007-318520 and No. 2008-042325 disclose a technique for generating a small-size electronic file from image data including texts, which is called “compact PDF”. Image data is divided into text areas and non-text areas, text areas having equal font colors are merged together to constitute one layer and converted to binary, then one color is defined in header information, which results in a reduction in the amount of text information. Meanwhile, the non-text areas are compressed after texts are removed therefrom such that they can be compressed at a higher JPEG compression ratio. With this technique, file size can be reduced accordingly.
Japanese Unexamined Patent Publication No. 2010-278948 suggests a method for adjusting the resolution to control file size within a specified value.
The technique described in Japanese Unexamined Patent Publications No. 2007-318520 and No. 2008-04232, however, has an unresolved problem as described below. Users can set the resolution low to reduce file size, but readability is negatively affected by deformation of small font-size characters and complex characters (Kanji characters, for example). Alternatively, users can set the resolution high to ensure readability, but there is a problem of increasing file size.
Without even a change in resolution, users can improve readability by a combination of various image quality adjustment processes such as background level adjustment, text sharpness level adjustment, and edge enhancement level adjustment. However, it is never easy to take trial and error with a sufficient knowledge of image processing.
Users may hope to configure the resolution settings for each page in image data depending on the page characteristics; for example, users may set the resolution low for a page including large font-size characters or alphabets characters and set the resolution high for a page including small font-size characters or Japanese characters. However, such a configuration is not commonly available.
Japanese Unexamined Patent Publication No. 2010-278948 suggests a method which does not bring a resolution to the above-described problem either. That is, with a reduction in resolution, readability is still negatively affected by deformation of small font-size characters and complex characters (Kanji characters, for example).